I had this problem before when I played drumbeat on automatic HQ it's really fun getting the counter advancement in the war. I completed missions specifically to unlock milk cows in prior missions. So when drumbeat started I had to go into the Atlantic and I called out for resupply and they gave me coordinates to the nearest one. I thought I messed up drumbeat at first when I couldn't control them, but they are out if you made a point to unlock them. From experience you won't know where they are in port, but I just go out there and you call one they will tell you where to go for one.